Me find the values of a and b so that the system shown had the given !

Quick translate "x is 12 units from 20" into an equation. what are the values of x being described? if you can answer any of my other questions that'd be great too

Candy lives in the center of town. her friend darlene lives 28 miles to the east and her friend dana lives 21 miles north. approximately how far do dana and darline live apart ?

Plz ( true - false) all triangles have interior angles whose measure sum to 90.